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The stem bears buds. The buds produce leaves or flowers. Often the flowers are between the stem and the leaf.
Coofee and maize flowers
Flowers can also grow at the tip of the stem.
All the plants you grow have flowers.
· The cotton flower is like the hibiscus flower. There are flowers which are alike; they belong to the same family.
· The cotton flower is not like the maize flower. There are flowers which are different; they do not belong to the same family.
· The flowers of rice, maize, sorghum are pressed close together round an axis, a main stem. They make a spike. The flowers of coffee and hibiscus are not pressed close together.
· There are flowers of all
colours: reds, yellows, violets, greens, greys.
For instance, grass flowers
are green,
Let us look at a hibiscus flower, or one of cotton, which has been cut in half with a razor blade.
The stamens are male organs.
The ovary is the female organ.
Hibbiscus flow cut in halt
Around the ovary and the stamens there are protective organs.
Let us look at a groundnut flower.
The stamens are male organs.
The ovary is the female organ.
Groundnut flower cut in half
Around the ovary and stamens there are protective
organs.
They protect the stamens and the ovary.
A groundnut flower
Let us look at a maize plant.
· At the tip of the stem there are a lot of little flowers.
They have stamens but no ovary.
They are male flowers.
· In the middle of the stem there is the spike (see page 6).
It consists of many flowers. Each flower has an ovary but no
stamen.
These are female flowers.
Each flower, each ovary, produces a
fruit, a seed.
· The male flowers and the female flowers also have protective organs.
A maize
plant
These are the most important parts of a flower.
Let us now
look in more detail at each of these parts.
This will help you to understand
the rest of the course.
· The male organs. Each stamen consists of a thread with a little bag at the end. In this little bag there is a yellow powder. This is pollen. If you touch the stamens of a flower, pollen sticks to your fingers. Pollen is produced by the stamens.
Not all flowers have the same number of stamens.
The hibiscus flower has many stamens.
The groundnut flower has ten stamens.
At the top of the maize stem there are many flowers.
Each
male flower of maize has three stamens.
A hibiscus flower
· The female organs.
With a razor blade we will cut in half an okra flower, or a
cotton or hibiscus flower.
The ovary is full of little white grains. These
are the ovules.
The ovules will produce the seed.
Hibiscus flower cut in half
· From the ovary grows a long tube, called the pistil.
The pistil of a hibiscus flower carries five little red globes
covered with moist hairs.
The pistil of a coffee flower has only one globe
.
The pistil of the female flowers of maize is highly developed.
On the
female flowers of maize you can see many pistils (they look like hairs).
At
the end of each pistil there is an ovary that produces a seed.
If you cut off
the pistils, there will be no
seed.
Take a hibiscus flower.
The male and female organs are protected by five red
petals.
These petals go all round the flower.
At the base of the petals is
a little bowl made of five green leaves. This is called the calyx.
Hibiscus flower seen from below
When the flower opens, the petals come out of the calyx.
The
calyx and the petals protect the inside of the
flower.
A plant flower has always: a male part the stamens; a female part the ovary; around these two parts the protective organs.
Stamens and ovary can be in the same flower, for example, hibiscus, okra, cotton, pimento, tomato, tobacco.
Stamens and ovary can be in different flowers. Then there are male flowers and female flowers, for example, in maize and oil palm.
Stamens and ovary can be in different flowers and on different plants.
In the papaya tree, the male flowers and the female flowers are not on the same tree.
There are male papaya trees and female papaya trees. Only the female papaya trees bear fruit.
The male papaya trees cannot produce fruit, but sometimes papaya trees that have male flowers do produce fruit.
A male papaya tree & A female
papaya
tree
Flowers have male organs and female organs. The union of pollen and ovule produces a seed. The seed can produce a plant.
· How does the union of pollen and ovule take place?
The stamens produce pollen. The pollen is very light. Wind or insects can carry it a long way. The pistil hairs are moist. Pollen sticks to them. The pollen germinates in the pistil as a seed germinates in moist earth. The pollen penetrates inside the ovary and into the ovule. The ovule is fertilized.
Coffee flower cut in half
Fertilization is the union of pollen and ovule.
If the flower dries up before the pollen arrives, there is no fertilization.
When the pistil is dry, the pollen cannot germinate.
A very dry wind, for instance, can prevent fertilization and reduce the harvest.
After fertilization the ovary and the ovules swell.
The ovary becomes the fruit. The ovules become seeds.
If the ovary has only one ovule, the fruit will have only one seed, for instance, mango, avocado.
If the ovary has several ovules, the fruit will have several seeds, for instance, orange, papaya, bean, coffee.
The two ovules have produced two seeds
Coffee fruit & Coffee fruit cut
in
half
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